1. Field of the Invention
The invention relates to a barometer.
2. Description of the Prior Art
Barometers with vacuum housings, known in numerous different embodiments, are designated aneroid barometers. The vacuum housing of these barometers is generally made solid with the instrument on one side, so that the metal diaphragm on the other side of the vacuum housing makes a corresponding movement in case of a change in air pressure. This translational movement or deflection is transmitted by a transmission mechanism to a pointer on a pointer shaft whose position can be read on a dial. The transmission mechanism must magnify the small deflections of the vacuum for reading and for this purpose has a great transformation ratio. The transmission mechanisms of known barometers generally comprise several levers which are made as one-armed, two-armed levers or angle levers, and elements made as chains, wires or tooth segments which finally transmit the movements from the lever mechanism to the pointer shaft. These transmission mechanims therefore consist of comparatively many parts, so that their production and assembly cost is high.
Further, a barometer is known (DE-AS No. 26 16 315), which already exhibits a simplified transmission mechanism. With this known barometer, the helical element is made like a helical spring. It is placed coaxially with the output shaft on the vacuum box and participates in its deflection. The helical element works with the output shaft through a pin that projects radially from the output shaft between the windings of the helical element. When the helical element is moved during the translational movement of the vacuum housing, it forces the output shaft, which is axially integral with the instrument, to perform a pivoting motion which is also imparted to the pointer shaft which in turn is unitary with the output shaft. Although the transmission mechanism of this known barometer offers lower production cost in comparison with the transmission mechanisms described in the introduction, a further reduction of production and assembly cost is desirable. Moreover, this known barometer has the drawback that its transmission mechanism functions in a comparatively inaccurate manner.